This application claims the priority of German Patent Application 101 20 841.3, filed Apr. 27, 2001, and German Patent Application 101 25 078.9, filed May 23, 2001, the disclosures of which are expressly incorporated by reference herein.
The invention relates to a hydraulic drawing system for a press which is provided for controlling a blank holder.
A known hydraulic drawing system is described in the journal INFORM 2/2000, Pages 54 to 55. Additional drawing systems of this type are known, for example, from DE 197 56 911 A1, DE 44 05 909 A1, EP 0 417 752 B1, and EP 0 417 754 B1.
With such drawing systems, good drawing results. That is, workpieces of a very high quality, can also be reached on single-acting presses. A problem of the known drawing systems is, however, their relatively slow response as well as the often very high-expenditure construction of the entire system.
An object of the present invention is, therefore, to provide a hydraulic drawing system for a press which results in a faster response and in a simpler construction of the entire drawing system.
According to the invention, this object is achieved by a system with a first line for directly connecting the pressure chamber with a control block provided for controlling the movements of the at least one cylinder-piston unit, and at least one storage element for storing pressure for the at least one cylinder-piston unit operatively connected by a second line with the control block, and at least one valve device being connected by a third line with the control block, the lines each extending at least approximately completely within respective components.
As a result of the control block, which is connected directly with the pressure chamber of the at least one cylinder-piston unit and which, in addition, has integrated connection lines to the storage element and to the valve device, faster regulating operations are achieved for the at least one cylinder-piston unit, which is directly reflected in shorter response times for the drawing system. Together with the control block, the storage element and the valve device, the at least one cylinder-piston block forms a module-type component in which all control and regulating operations take place for achieving the functions of the drawing system.
This results in a very compact and extremely rigid module which has a by far lower vibration susceptibility than previously known solutions and by means of which a very dynamic regulating behavior can be achieved. Furthermore, this compact construction results in a very easily accessible and, for this reason, mounting- and maintenance-friendly structure of the entire drawing system.
In an advantageous further development of the invention, the required force for the drawing system can be uniformly distributed in that the drawing system is provided with several cylinder-piston units, each cylinder-piston unit having a control block and storage elements mounted on the respective control block as well as valve devices.